In the field of communications over a network it has become widespread the use of packet switched services over broadband access networks, which are typically packet switched networks. One service which has become increasingly popular is the transmission of voice over packets, according for instance to the Voice over Internet Protocol, VoIP. The problem of interworking between VoIP services and existing circuit switched voice calls provided in existing circuit switched networks is typically solved by means of interworking nodes specifically implemented in the network. Thanks to the interworking, users of packet switched voice services over packet switched networks can interoperate also with users of traditional circuit switched voice services.
More recently, network operators and users have experienced an increased need of making also circuit switched calls or packet switched network. In other words, on one side there is the problem of interworking packet switched services such as VoIP with circuit switched networks, while on the other side it has become important offering circuit switched calls and services to packet switched users.
Through the deployment of low cost fixed broad band accesses and increased backbone network capacity, voice has turned from a niche Voice over IP application into a key service enabled by IP networks. This is especially visual through VoIP implementations like Skype.
Skype hereby imitates and enhances (video, presence, . . . ) the traditional circuit switched voice service for calls inside the IP network. In order to interwork with the traditional circuit switched voice service, Skype deploys gateways, which mediate between the Skype voice service and the circuit switched voice service. The ease of installation, the look and feel, the “good enough” voice quality and the low usage fees have been instrumental for Skype's success.
At the same time, the mobile voice access continues to be dominated by the traditional circuit switched mobile system, like the mobile soft switch. The mobile soft switch is a network entity for controlling a variety of functions in relation to communications within the network. The soft switch may be comprised in one physical device but is typically distributed over several physical devices in order to partition the distribution of functionalities within the network. With soft switch it is made reference to network entities such as exemplarily comprised in network architectures according to 3GPP specifications, see e.g. TS 23.002. Mobile service providers in developed countries continue to achieve 50-90% of their income through the mobile voice service and do not have any incentive to move away from the mobile voice service. On emerging markets the infra-structure for fixed broad band accesses is usually not available, nor economically feasible. This makes the mobile circuit switched networks the prime choice for deploying voice services.
Wireless and mobile broadband accesses capable of carrying voice are now emerging through WLAN, WiMAX, HSPA, LTE. This gradually enables fixed type of VoIP services like Skype to be available also in a wireless and mobile environment. Telecom industry has developed the Internet Protocol Multimedia Standard (IMS) to handle services enabled by the increasingly broad band access networks. The multi media telephony service (MMtel) is also present and targeting the VoIP markets. IMS systems are however not yet broadly deployed.
Today a user can either use a narrow band traditional circuit voice through a wireline or mobile phone, or a lower cost broad band access VoIP service. The advantage of having a low cost VoIP service also implies that the users need to make an active choice whether to use Skype, other VoIP services, mobile circuit voice or fixed circuit voice. This choice is influenced on their geographical position, the device they want to use, who they want to reach, what the other party tends to use, the length of the conversation, the price they are prepared to pay, how much money they have on their prepaid account for the service, the services they want to invoke including the kind of voice quality they want to have etc. Thus, an active choice is needed that makes the use not straightforward.
Another problem for the users is that the user experience, the quality and the services offered vary with the choice made. For example a Skype user can have excellent speech quality one day and poor quality the next day, or the service might not be available at all.
The mobile service providers in developed countries notice the new wireless and mobile broadband accesses that now occur. There is an understanding that a certain amount of voice traffic will migrate from the circuit networks to the VoIP services. Today mobile service providers have limited means to benefit from the transition to VoIP. There is an expectation that IMS can play a future role in this, but proprietary implementation like Skype dominate as they are available already today. An uncontrolled voice migration would mean that large parts of the operators' income disappear.
Mobile service providers in developing countries want to secure that the investments in today's voice infrastructure can be used for a long time. A scenario where wireless and mobile broadband are added rapidly and rapid voice migration happens will discourage current voice infra structure investments.
Mobile and fixed service providers that embrace proprietary VoIP technologies, like Skype, for use in broadband networks face a number of challenges. Skype-like networks are in essence networks of their own that need to be built from scratch. This means that all aspects that have been developed and optimized over more than 100 years in circuit voice networks need to be re-implemented in the new VoIP networks. It is technically challenging, and thus also costly, to maintain a high availability VoIP service (in service performance, capacity, scalability, etc) and compliance to market and regulatory aspects in VoIP networks (market specific services, charging, monitoring, interconnect, etc). A further problem is that the gateways required for connecting proprietary VoIP networks, like Skype, to traditional voice circuit networks emulate functionality. This creates a significantly different look and feel for the VoIP users as compared for example to 2 GSM subscribers having a voice conversation.
Mobile and fixed service providers that embrace the IP Multi Media (IP MM) system face a similar situation as when wanting to deploy proprietary VoIP technologies broadly. This is due to today's limited deployment of IP MM and the need for gateways for inter-working scenarios.
Mobile and fixed service providers that enhance existing circuit switching voice equipment to support native SIP based VoIP services also face several challenges. SIP client access security either needs to be implemented directly in the switching nodes or access nodes that interwork between the accesses and switching nodes need to be introduced. Interworking between SIP based VoIP and circuit switched need to be defined and implemented with capability loss as a consequence. Network scalability and stability need to be solved too. Thus, a series of problems are still open.
Attempts are known in the art for connecting broad band accesses to existing mobile voice networks by placing a proprietary BSC/RNC emulation node between the broad band access and the mobile soft switch. Although there is interest from leading mobile service providers, the solution is not yet proven. Furthermore, it is a single source solution, introduces additional complexity to the network and faces the previously mentioned availability and scalability challenges.
It is also known in the art a communication node which is added to a known communication network for interfacing between a mobile switching server and one or more different access networks. The additional network device performs the interworking between services provided over a broadband access network and a mobile switching centre or between services provided over an INS network and a mobile switching server. It is remarked that this known solution performs an interworking on a network to network interface. However, also this known solution suffers from at least the same problems as above mentioned. For instance, the interworking causes the loss of functionalities since during the interworking process some functionalities may get lost due to the impossibility to convert or adapt all the native functionalities of one service into the functionalities of a different service. Furthermore, this solution adds to the complexity of a network and to its maintenance since it adds one more component to the whole network. At the same time, low reliability and low scalability of the known solution are still a problem.